Question

Jennie has a jar of 54 coins consisting of dimes and quarters. If she has a total of $11.10, how many dimes does she have?

Answer 1

d + q = 54
d(10) + q(25) = 1110

Do you know substitution?

Answer 2

no not really

Answer 3

Okay, here are the steps then.

First find q(quarters) in the first equation.
d + q = 54
Subtract d.
q = 54 - d

Now put the value of q into the second equation.
10d + 25q = 1110
10d + 25(54 - d) = 1110
Distribute. Solve for d(dimes)
10d + 25(54) + 25(-d) =1110
10d + 79 - 25 = 1110
10d + 54 = 1110
Can you solve from there?

10d + 54 = 1110

Answer 4

Is it 16 or 22?

Answer 5

so it is 16?

Answer 6

One sec...

Answer 7

10d + 25(54) + 25(-d) =1110
10d + 1350 + 25(-d) =1110
@jazy thats the mistake i caught

Answer 8

Okay! Thanks @sudawi
Yes you're right @Eulie it is 16.

10d + 25(54) + 25(-d) =1110
10d + 1350 + 25(-d) =1110
10d + 1350 - 25d = 1110
-15d + 1350 = 1110
Subtract 1350.
-15d = -240
Divided by -15
d = 16